Some kinds of landing gear are fitted with deflectors to prevent stones or debris being thrown up or “lofted” by the tires while the aircraft is running on the ground.
Such deflectors are commonly mounted in particular on the nose landing gear of Russian fighters such as the MIG 23 or the MIG 29, where such landing gear has two wheels on a common axle. The deflectors are then in the form of a flap extending behind the tires of the landing gear and mounted to pivot about an axis that coincides with the axis of the axle, the deflector also being connected by a rod to a fixed point on the main strut of the landing gear. Thus, the greater the extent to which the shock absorber of the landing gear is pushed in (which corresponds to a large static load on the landing gear and thus to an increased risk of stones being lofted), the closer the flap of the deflector approaches the ground.
Nevertheless, clearance must necessarily be maintained between the ground and the bottom of the flap in order to prevent the flap from scraping the ground and being damaged, or indeed from preventing the aircraft from being movable rearwards (e.g. when pushed by a tractor). The need to take account of the potential of the tires being under-inflated has led to providing a large amount of clearance between the ground and the bottom of the flap, thereby reducing the effectiveness of the deflector.